This PR is a cherry-pick of #63766 to release/10.7.

Original PR Description

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• I have followed the WooCommerce Contributing Guidelines and the WordPress Coding Standards.
• I have checked to ensure there aren't other open Pull Requests for the same update/change.
• I have reviewed my code for security best practices.
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Fixes WOOPLUG-6360 WOOPLUG-6047

Changes proposed in this Pull Request:

This PR implements two related features for the WooCommerce Fulfillments system:

WOOPLUG-6360: Custom Shipping Providers

• Registers a wc_fulfillment_shipping_provider WordPress taxonomy to store custom providers
• Adds a CustomShippingProvider class extending AbstractShippingProvider with tracking URL template support (__PLACEHOLDER__ replacement)
• Loads custom providers into the existing woocommerce_fulfillment_shipping_providers filter at priority 20 (after built-ins at 10)
• Adds a "Shipping providers" tab under WooCommerce > Settings > Shipping with a Backbone.js CRUD UI (following the exact shipping classes pattern)
• Adds an AJAX handler (shipping_providers_save_changes) for create/update/delete operations
• Custom providers automatically appear in the fulfillment form dropdown

WOOPLUG-6047: Filter by Shipping Provider

• Adds a "Filter by shipping provider" dropdown to the orders list table (both HPOS and legacy)
• Includes all built-in and custom providers, plus an "Other" option for free-text providers
• Filters orders by joining wc_order_fulfillments and wc_order_fulfillment_meta tables

Closes # .

Screenshots or screen recordings:

How to test the changes in this Pull Request:

Using the WooCommerce Testing Instructions Guide, include your detailed testing instructions:

Basic functionality

1. Enable the Fulfillments feature flag (woocommerce_feature_fulfillments_enabled = yes).
2. Navigate to WooCommerce > Settings > Shipping > Shipping providers.
3. Click "Add shipping provider" and create a provider with a name (e.g. "My Local Courier"), tracking URL template (e.g. https://example.com/track?id=__PLACEHOLDER__), and optionally a slug and icon URL.
4. Verify the provider appears in the table. Edit and delete it to confirm CRUD works.
5. Create a new order and open the fulfillment drawer. Verify the custom provider appears in the provider dropdown.
6. Select the custom provider and enter a tracking number. Verify the tracking URL auto-fills with the template (placeholder replaced).
7. Navigate to WooCommerce > Orders. Verify the "Filter by shipping provider" dropdown appears next to the fulfillment status filter.
8. Create fulfillments with different providers on several orders. Filter by a specific provider and verify only matching orders are shown.
9. Filter by "Other" and verify orders with free-text (non-listed) providers are shown.

Slug uniqueness and immutability

10. Try to create a custom provider with slug ups (or any built-in provider key). Verify it is rejected with an error message about the slug being already in use.
11. Create a custom provider with name "UPS Freight" and no slug. Verify the auto-generated slug is checked against built-in keys and rejected if it collides (e.g. if it auto-generates to ups).
12. Create a custom provider with a unique slug. Edit it afterwards. Verify the slug field is read-only in the edit modal and cannot be changed.

URL validation

13. Try creating a provider with an invalid tracking URL template (e.g. not-a-url). Verify the value is silently discarded (stored as empty).
14. Try creating a provider with an ftp:// or javascript: tracking URL. Verify it is rejected (only http:// and https:// are accepted).
15. Try creating a provider with an invalid icon URL. Verify it is silently discarded.
16. Edit an existing provider that has a valid tracking URL. Submit the edit modal with an invalid URL in the tracking URL field. Verify the previously saved valid URL is preserved (not wiped).
17. Edit an existing provider. Clear the tracking URL field entirely and save. Verify the tracking URL is now empty (intentional clear works).

Deletion protection

18. Create a custom provider (e.g. "Test Courier").
19. Create an order and add a fulfillment using "Test Courier" as the shipping provider.
20. Go back to WooCommerce > Settings > Shipping > Shipping providers and try to delete "Test Courier". Verify deletion is blocked with an error message explaining it is used by existing fulfillments.
21. Delete the fulfillment from the order. Now try deleting "Test Courier" again. Verify it succeeds.

Feature flag gating

22. Disable the fulfillments feature flag (woocommerce_feature_fulfillments_enabled = no).
23. Verify the "Shipping providers" tab no longer appears under WooCommerce > Settings > Shipping.
24. Navigate directly to ?page=wc-settings&tab=shipping&section=fulfillment-providers. Verify the providers screen does not render.

Placeholder icon (TruckIcon fallback)

25. Create a custom provider without an icon URL.
26. Create a fulfillment using this provider. Verify:
    • In the provider dropdown, a truck icon appears next to the provider name (not a blank space).
    • In the shipment viewer (collapsed fulfillment card), a truck icon appears instead of a broken image.

Testing that has already taken place:

• PHPUnit tests: 24 tests passing (8 for CustomShippingProviderTest, 16 for FulfillmentsManagerTest)
• JS tests: 26 tests passing (shipment-viewer, shipment-manual-entry-form, shipment-tracking-number-form)
• PHP linting: clean (phpcs-changed)
• PHPStan: clean (no new errors)

Milestone

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